Effects of Final Cooling Temperature on Low-Temperature Impact Fracture Behavior of Q500 Weathering Bridge Steel
For the bridge construction project in the complex environment of the plateau,the high impact resistance and low tough-brittle transition temperature weathering bridge steel with a yield strength of 500 MPa has been developed.The effects of the final cooling temperature after rolling on the microstructure and mechanical properties of the experimental steels were studied,and the effects of low temperature on the impact toughness of the experimental steels were analyzed in depth.The results showed that the experimen-tal steels after TMCP treatment could meet the mechanical property requirements of Q500 grade bridge steel,and the experimental steels with two different final cooling temperatures(500,550℃)showed good impact properties under the low-temperature environment of-40 to-80℃.However,with the increase of final cooling temperature,the grain size of experimental steels increased;the increase of M/A island size and change of morphology and the decrease of the proportion of large-angle grain boundaries were the main reasons for the difference in impact properties of the two experimental steels.
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